X-RAY REFLECTIVITY ANALYSIS OF THIN TIN AND TIOXNY FILMS DEPOSITED BYDUAL-ION-BEAM SPUTTERING ON (100)SI SUBSTRATES

We present an X-ray reflectivity study of thin TiN and TiOxNy films gr own on Si(100) substrate by the dual-ion-beam-sputtering technique. Th e thickness range of the deposited films varies between 25 and 35 nm. We demonstrate that low-angle X-ray reflectivity is a powerful tool fo r studying the early stages of growth and the surface and interface pr operties of these films. We found that an oxidation of the TIN film su rface occurs, yielding a 2 nm thick TiO2 film, if the films are expose d to air after the growth. Furthermore, an interface layer 1.5 nm thic k with electron density near that of SiO2 is present at the substrate- him interface. The thickness of the interface layer increases by more than three times after 7-8 months (aging). The formation of the oxide layers is independent of the growth mode, i.e. growth with and without ion assistance. In addition, the formation of a TiO2 surface layer is also observed for TiOxNy films. The samples synthesized by employing ion-beam assistance show a much lower surface roughness (similar to 0. 8 nm) compared to the samples deposited without ion-beam assistance (s imilar to 1.5 nm). This finding demonstrates that films with improved structural and surface properties can be obtained by using dual-ion-be am-sputtering. (C) 1997 Elsevier Science S.A.